Integrated circuits typically use bonding pads to provide the electrical connections between the integrated circuits and the package substrate, or whatever other element the integrated circuit is interfaced with, such as a circuit board. As the term is used herein, “integrated circuit” includes devices such as those formed on monolithic semiconducting substrates, such as those formed of group IV materials like silicon or germanium, or group III-V compounds like gallium arsenide, or mixtures of such materials. The term includes all types of devices formed, such as memory and logic, and all designs of such devices, such as MOS and bipolar. The term also comprehends applications such as flat panel displays, solar cells, and charge coupled devices.
On one side of the logical electrical circuit, the bonding pads form electrical connections to “the outside world.” On the other side of the logical electrical circuit, the bonding pads form electrical connections to the other elements of the integrated circuit. Thus, power, ground, and signal connections are all typically formed through the bonding pads.
In wire bonded integrated circuit designs, the bonding pads are typically placed in one or more concentric rings or rows that are disposed around the edges of the chip. Bonding pads for the power and ground services are typically placed on the outermost ring of bonding pads, which are disposed closest to the peripheral edges of the chip. Thus, there are typically one or more concentric rings of bonding pads disposed between the power and ground bonding pads and the active circuitry that requires the power and ground services.
The power and ground services are routed from the bonding pads on electrical leads called pad wires. Pad wires are typically formed in the same metallization process as the bonding pads themselves. The bonding pads in the different concentric rings are typically staggered from row to row, and the pad wires from the power and ground bonding pads in the outer-most row of bonding pads are routed between the bonding pads of the inner rings of the bonding pads. The pad wires are then respectively electrically connected to the power and ground meshes that are typically disposed interior to the innermost ring of bonding pads.
These separate power and ground meshes deliver power and ground services to all of the circuitry in the integrated circuit. The meshes typically reside on a lower layer of the integrated circuit, below the layer in which the bonding pads and pad wires are formed, and also below the dielectric layer that directly underlies the bonding pads and pad wires. Electrically conductive vias through the dielectric layer are used to make the electrical connections between the pad wires and the meshes.
What is needed, therefore, are systems for distributing power and ground services within integrated circuits, which systems fill various needs of the integrated circuit.